The invention relates generally to packet shaping for transmissions in an IEEE 802.11 network.
A wireless local area network (WLAN) based on the IEEE 802.11 standard supports variable packet length. When such a network supports multi-rate communications, even packets with the same size may require different transmit durations at different rate modes. As a result, a node operating at a lower data rate may require a longer transmission time than higher rate nodes in order to transmit the same amount of information. The IEEE 802.11a standard sets a uniform maximum packet length limit of 4095 bytes regardless of the data rate, but allows PHY mode rates to range from 6 Mbps to 54 Mbps. Thus, the time that a 6 Mbps node occupies the network channel may be up to nine times that of a faster 54 Mbps node. This type of scenario is undesirable because the presence of low data rate nodes significantly reduces overall network capacity.